ness of these programs, and pointed out program and methodological gaps. He ended his presentation with his own suggestions.

Conceptual Analysis

Ribar observed that the use of a conceptual model helps in the understanding of how children get fed and why some go hungry, provides insight into how various programs work, and helps identify potential challenges for program effectiveness. Ribar pointed to the Gundersen discussion in Chapter 2 on the development of conceptual models, to the Institute of Medicine and National Research Council (IOM/NRC) report (2013), and specifically to Barrett’s (2002) model of how household food security is determined. The Barrett model adapted Becker’s (1965) household production model, and is very similar to Grossman’s health production model (1972). Ribar used the Barrett model in his discussion.

The model assumes a household that faces a life-cycle utility function with two objectives in each period. One is to advance its physical wellbeing, and the other is to consume things based on a preference function that incorporates tastes and culture. Finally, the model assumes that the household will discount the future and that the future will be uncertain.

Ribar explained that in the model, physical well-being in a given period is based on the previous status of physical well-being augmented with inputs of nutrition, activities (such as rest and exercise), nonfood consumption, financial constraints, and other things. It is subject to shocks from illness or injury. Nutritional inputs are based on inputs of food and the household member’s time. Their effectiveness is conditioned on the member’s health as well as his/her skill and knowledge.

Ribar then described potential outcomes. The household in this model chooses work, activities, and the consumption of food and nonfood items so as to maximize its objectives subject to its constraints. Through its decisions, the household might achieve one of three levels of food security: sufficient for survival, sufficient for nonimpairment, or sufficient for health. U.S. policies typically focus on achieving good health, while survival and nonimpairment are important focuses in developing countries.

He said that within this standard framework for household decision making, Barrett (2002) pointed out six types of static structural threats to food security: (1) low labor productivity (a limited ability to work or to earn, which results in fewer resources available to the household); (2) adverse terms of trade for a given level of work or abilities (the household member is not able to command a very high wage and/or may face high food prices); (3) lack of access to markets where household members could engage in paid labor or purchase goods; (4) asset poverty (low lev-



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